rust: remove Deref in favor of explicit methods
Differential Revision: https://phab.mercurial-scm.org/D6593
rust: simplify overly complicated expression
Differential Revision: https://phab.mercurial-scm.org/D6592
rust: run rfmt on all hg-core/hg-cpython code
Differential Revision: https://phab.mercurial-scm.org/D6591
debugrevlog: fix average size computation for empty data (
issue6167)
If the file has no full snapshot (eg: was always empty), `hg debugrevlog` would
fails when trying to compute their average size.